Many gaskets today are fabricated from a molded plastic carrier with which elastomeric seals are associated. The elastomeric seals may be perimetric seals, such as ones which circumscribe such a gasket on each of its major faces, or which may be edge molded to an edge surface of the gasket. Gaskets having such seals may also employ sealing elements for the inner surfaces of openings, such as bolt holes. One usual technique for associating sealing elements with a carrier comprises the edge molding of a sealing element to the carrier and securing its adhesion with the aid of a chemical adhesive. Another technique is to mold perforated plastic carrier projections in a carrier opening to be sealed. Molten liquid sealant will flow through the perforation and will set up as the sealant solidifies, thereby to secure the sealing element in place.
In many environments techniques such as those are disadvantageous. For example, the use of adhesive securance techniques typically requires an expensive adhesive and additional handling, and does not permit the straightforward molding of an elastomeric seal in situ. In the case of the use of perforated projections, they require a longer engaged length of the final seal because of the necessary length of the perforated plastic projections.
It would be desirable to provide an edge molding technique for openings and the like for effectively securing perimetric seals so that they may be molded in situ without requiring either extraneous adhesives or the longer engaged length which projecting perforated plastic projections dictate, and which technique will also permit the use of but a thin layer of sealing material to provide the necessary seal.
In accordance with the present invention, a method of making a gasket having an elastic seal molded thereto is provided comprising the steps of providing a molded plastic carrier defining a carrier surface against which an elastomeric seal is to be molded, the carrier surface defining a plurality of anchors projecting therefrom, each anchor comprising a hub extending outwardly from the carrier surface and a protuberance at the end of the hub, the hub having a first cross-sectional dimension and the protuberance having a second cross-sectional area which is at least twenty percent greater than the first cross-sectional area, then molding an elastomeric seal against the carrier surface by flowing molten elastomer to fully embed the hubs and protuberances within the molten elastomer, whereby when the elastomer solidifies, the anchors secure the elastomeric seal to the plastic carrier. In one form the carrier surface comprises a wall of an opening through the carrier. In a preferred form the protuberance is a plate spaced from the carrier wall surface by the hub, and the carrier wall surface comprises a generally cylindrical opening and the hub projects radially inwardly of the cylindrical opening.
The invention also comprises a gasket having a plastic carrier and an elastomeric seal molded thereto, the plastic carrier defining at least one opening therethrough and having a wall surface therearound. The elastomeric seal is molded to and against the wall surface. The wall surface has a plurality of anchors projecting inwardly therefrom, each anchor comprising an inner member and a hub connecting the inner member to the wall surface, the hub having a cross-sectional dimension which is less than the cross-sectional dimension of the inner member, the anchors being embedded in the elastomeric seal thereby securing the seal in the opening and against the wall surface.
Further objects, features and advantages of the present invention will become apparent from the following description and drawings.